Hydraulic brake



- April 18, 19445 c. E. FEDERIcKsoN 2,346,833

` HYDRAULIC BRAKE Filed Feb. v12, 1943 6 SheetS-Sheeb 2 nia- [Il l I ,ff/W

C'Zazyon ederz'lc/som April 18, 1944. c E. FREDERlcks-ON y HYDRAULIC BRAKE u Filed Feb. 12, 1945 6 Sheets-Sheet 5 April 18, 1944. c.-E. FREDERICKSON 2,346,833 I HYDRAULIC BRAKE Filed Feb. 12, 1943 Sheets-Shee't 4 April 18, 1.944, c. E. FREDERxcKsoN 2,346,833

HYDRAULIC BRAKE Filed Feb. 12, 1943 6 Sheets-Sheet 5 April 18., 1944.

c. E. FREDERlcKs'oN HYDRAULIC BRAKE Filed Feb. 12. 1943 *l Dbl/*Wa e sneejcs-sneet s a'y'oml: ecerzlokson/ Panarea Apr.- is, 1944 UNITED STATES PATENT ort-ica mamme Bama clayton Erasmus Frederickson, chicago, nl. Application February iz, 1943, serial No. 475,849

2o claims.r (ci iss-si) MY invention relates to the art of vehicle brakes and it particularly has for its object to provide an effective brake which is especially adapted for use on the wheels of airplanes.

Primarily the invention seeks to provide a simple, powerful hydraulic brake of a compact structure, one that is relatively light in weight, one that can be incorporated in an airplane wheel without much change in the design of the wheel, and one that will be relatively inexpensive to manufacture and install.

Another object of the inventioniis to provide a hydraulic brake, located within the wheel, which is so constructed that the wheel is well balanced so that. when no brake application is desired, the wheel may turn freely on its axle.

Again, it is an object to provide a hydraulic brake within the wheel, the mechanism of which is operatively controlled by means located in part within the axle on which the wheel turns.

Again, it is an object to provide means wherebythe cylinders are protected against giving way under excessive pressure.

Further, it is an object to provide, in a modified form, means for taking the torque strains from the shifting key s that a shorter shifting key can be used than in the first embodiment of the invention.

Other-objects will in part be obvious and in part will be pointed out hereinafter. e

To the attainment of the aforesaid objects and ends the invention further resides in the novel details of construction, combination and arrangement of parts, all of which will be` rst fully described in the following detailed description, and then be particularly pointed out in the appended claims, reference being made to the accompanying drawings, in which:

Fig. 1 is a central vertical longitudinal section of a preferred embodiment of my invention.

Fig. 2 is a transverse section on the line 2-2 of Fig. 1.

Fig. 3 is a transverse section on the line 3-3 of Fig. 1.

Fig. 4 is an elevation of one face of one of the wabbler plates.

Fig. 5 is an elevation of the other face of the same.

Fig. 6 is an elevation of one'of the yoke members and the side plate of the rotor to which it is pivoted.

Fig. 'I is an elevation of the male friction clutch member.

Fig. 8 is an elevation of one of the toothed clutch members.

modification of the form oi' the invention shown in Fig. 1.

Fig. 11 is a detail section of one kind of pressure-relief valve that may be used.

In the drawings, in which like numerals .of reference indicate like parts in all the figures, i represents the stationary shalt or axle on which the wheel is mounted. The axle `I is counterbored as at 2, thus providing a shoulder 8 against which a washer 3 is held by the threaded plug 3 which is screwed into the threaded part 4 of the axle.

Near its outer end the axle l is further counterbored, as at 5, adjacent which end there is provided a groove I to receive the split ring i8. The axle also has a cross slot i for the key i5.

lThe plug 3 is bored and tapped to receive the oil line i3 which leads oil .from the aviators brake-applying pedal to the counter-bore 2. At one side of the key i5, and within the counterbore 2, is a piston Il carrying a packing cup l2 which is secured to the key I5 by a bolt i4 and nut i3. At the other side of the key i5. and within the counter-bore 2, is a return spring I8, a pair of sealing discs I1 (held by a wire ring 91), and asealingringl (seeFigl). f

IThe axle l has shoulders I8` and 2l, against which are held discs 20 and 24. The axle is threaded at its outer end, as at 22, to receive the castle nut 23.

The wheel proper comprises the sides 26 and 35, the tire retaining anges 26 and 36 (the latter being removably held in place by the locking ring the annular center portion 45, and the bolts and, nuts 31 which hold the side plates 25 and 35 and the central portion 46 together. The vside plates 25 and 35, respectively, have tubular hubs 21 `and 31 whose outer ends are recessed, as at 28 and 38 respectively, to receive the discs 20 and 23. The hubs 21 and 31. are bored, as at 29 and 39 respectively, to receive the anti-friction bearings 33 and I0, respectively. The hubs l are further bored, as at 3i and to receive the oil seals Fig. 1.

The side 25 ot the wheel has an inclined slideway 33, while the side 35 has an inclined slideway 43, thefslideways being inclined in opposite directions as shown in Fig. 1. The sides oi.'V the wheel vare also provided with recesses 34 and M respectively. l

Within the wheel and normally freely rotatable I I, respectively, 32 and 32, as shown in wabbler.

on the axle is a rotor. In the embodiments of my invention illustrated in the drawings, the rtor comprises a pair of spaced side discs 48 and 49 having hubs 50 suitably bushed as at 5|. Between these discs are mounted cylinders 52 by means of lugs 59 and screws 54, the axes of the cylinders lying parallel with that of the axle I and spaced equidistant therefrom. The cylinders each have oil inlet apertures 55 and a fluid outlet nipple 58. The nipples have inclined faces 51 to cooperate with the frusto-conical face 84 of a valve 83, hereinafter more fully explained. -Within each cylinder 52 is a pair of opposed pistons 5B. Each piston 58 is connected to a Each wabbler includes a yoke 6| having a pair of stub shafts 62 radiating therefrom, and a slide plate 83 having radially dispcsedhalfbearings 64 for the stub shafts 82, and having connecting-rod bearing sockets 68. Rods 59 connect the pistons 58 with their respective wabbler slide platos. Other half-bearings 85 cooperate with the half-bearings 84 to hold the plates to the yokes 8|. The half-bearings 65 are held in place by screws 88. Y

The hubs 50 have ears 60 to which the yokes are pivoted on trunnion pins 81. ,The axis passing through the stub shafts 62 lies at right angles to that passing through the trimnion pins 81. Thus the wabblers are universally mounted on the respective hubs 50 of the rotor and function as a part of the'rotor, Y

Mounted to turn on the axle I adjacent the key slot 1 is a ring 89 and a major clutch sleeve 10. The ring 69 and sleeve 10 are secured together to slide on the axle. The sleeve 10 has clutch teeth 1| to mesh, at times, with the clutch teeth 14A on the disc o r plate13 that is attached to the side disc 49 of therotor by bolts 15. The sleeve 10 also has key sockets 12 to receive the key l5. which prevents the sleeve from turning on the axle. I

Secured to the ring 89, by screws 1.1 or in any other suitable way, is a minor clutch sleeve 16 having clutch teeth 18 to mesh at times with clutch teeth 80 on a ring 8l that is secured to left in Fig. 1.

the side discs 48 of the rotor by means of screws v 82. The sleeve 18 has a flange 19 to which is fastened, in any suitable way-as by screws 85- the valve 89 hereinbefore referred to.

Secured to the side disc 49 of therotor by screws 88, or in any 'other suitable way, passing through its flange 81 is a cylinder 88 having a female friction clutch face 89 preferably of the cone type. A shiftable male. friction clutch 9| has its clutch face 90 disposed to cooperate with the face 89 at times, as will more clearly appear later. The clutch 9| is keyed to the sleeve 10 by keys 92 and is constantly urged toward its clutching position by a cone-shaped spring 94 that exerts as much power open as when closed. The clutch 9|, while it is keyed to the sleeve 10, is also slidable on the sleeve. The spring 94 lies between the flange 93 and the valve 83.

of the hubs 50'-; the shifting key |55 is made narrower than the key I5 and the ring 89 and ,sleeve 10 (Fig. 1) are made in one and numbered 10n in Fig. 10; long keys |00 secure the sleeve 10* to the shaft against rotation while permitting the sleeve to slide along the shaft l,

The embodiment of the invention shown in Fig. 10 also differs from that of Fig. 1 in that the outlet nipples 56' are-longer than those in Fig. l and the valve 83* is correspondingly smaller, so that I may provide pressure-relief safety valves |01 to permit escape of iiuid, should the pressure within the cylinder be great enough to burst the cylinders. Any suitable pressure-relief valve may be used. For illustrative purposes I have shown a valve in Fig. ll which may be used. The safety valve shown in Fig. 11 consists of a casing having a valve seat |02 for thevalve |03. held seated by a spring |05. in the neck |04, which spring presses against the valve and against a disc |06 having a conical depression for the end of the adjusting screws |01, a lock nutl |08 being provided for the usual purpose.

Operation V'faces 89 and 80 lie close together but are not in contact; the clutch teeth 1| and 14 lle wide apart, as do also the teeth 18 and 80. The normal space between the teeth 1| and 14 and that between the teeth 18 and -80 is the same, or approximately so. The space between the valve face 84 and the faces 51 of thecyllnder oil outlet nipples issuch that the clutch teeth 1|-14 and 18-00 must be fully meshed before the valve 83 will fully close the outlets 55.

Now. with the parts positioned as just before described, when the aviator desires .to apply the brake, he forces fluid through the pipe |0 into the chamber between the plug 9 and piston and thereby causes the piston to move from right to The movement' of the piston is transmitted through the key Il to the sleeve 10 and to the ring G8 and the sleeve 16. As sleeve 18 carries the female friction clutch 8|, the frlcstood that the farther the piston is'forced to Suitably located oil passages 95 are provided in the discs 48 and 49 and in the valve 83.

Caps 98 hold the ball ends of the connecting rods in the sockets 88.

The'embodiment of the invention shown in Fig. l

ward the left, the more completely the clutch teeth will be engaged and the more fully the outlets 5i will |be closed.y Themore fully the outlets 50 are closed, the greater the friction between the wabbler faces and the slideways and hence the more powerful the A'braking action until the wheel is hydraulically locked to the axle when the outlets 56 are fully closed.

On releasing the brake clutch the .teeth come out of mesh before the friction clutch faces separate. Because of the fact that the friction clutch, during the application of thebrake, engages rst and reduces the speed ofthe wheel to approximately zero, there'will be no clashing of teeth while the toothed clutches are being brought into mesh. l

rI 'hose parts inFig. 11 which correspond to like lor similar parts in the preceding figures bear the same reference number plus the index letter a, so a detailed description of Fig. 11 is thought tobe unnecessary.

The valve is ascenso Changes and modiilcations in the detalls of construction and arrangement ot parts may be made without departing from the invention within the scope of the appended claims.

This application is, in part, a continuation of my application tiled December 12, 1942, Ser. No. 467,- 878.

From the foregoing description. taken in connection with the accompanying drawings. it is thought the complete construction, operation and advantages of my invention will be clear to those skilled in the art.

What I claim is:

l. A wheel having a rim and sides provided with hubs: an axle on which said wheel is mounted, said wheel and axle enclosing a chamber for retaining hydraulic duid; a rotor located within said wheel and rotatably mounted on said axle: an inclined slideway on the inside oi the wheel: a. imiversally mounted wabbler having a plate irictionally cooperatively engaging said slideway: said rotor including cylinders and pis. tons with connecting rods between the pistons and said wabbler. said cylinders having piston controlled iuid inlets and having huid outlets; means for ilrst frictionally clutching said roto:` to said axle and subsequently positively securing said rotor to said axle: and means for con-trolling the escape of uid from said cylinders for purposes described.

2. A chambered wheel having hubs; an axle on which said hubs are mounted: an inclined slide way within the chambenof the wheel; a rotor located within said chamber and rotatably mounted on said axle, said rotor including side discs. cylinders connecting the side discs, pistons in said cylinders, a wabbler, and connecting rods between said pistons and said wabbler. said wabbler being engaged with said slideway. said cylinders each having a liquid inlet and a liquid outlet; a friction clutch connection between said axle and said rotor; a toothed clutch connection between ing engaged with said slideway, said cylinders each having a liquid inlet and aY liquid outlet: a friction clutch connectionbetween said axle and said rotor: a toothed clutch connection between said axle and said rotor; means operating first to engage said friction clutch and upon further movement to engage said toothed clutch connections to stop the rotor; means to operate said clutch connections to de-clutch the rotor from the axle; and a valve device common to all said cylinder outlets for retarding the ilow of liquid through said outlets while the clutches are in action.

5. A wheel comprising a hollow body having sides with hubs and having an annular rim connecting said sides to enclose therewith a iluid containing chamber, said wheel having an annular inclined s lideway: an axle on which said wheel is rotatably mounted: means to seal the wheel and axle against escape oi the liquid contents of the wheel; a rotor including spaced discs having hubs rotatably mounted on said axle,

,cylinders connecting said spaced discs, said cylinders each-having iiuid inlets and outlets: a wabbler including a yoke pivotally mounted on one of said discs; a slide plate pivotally mounted on said yoke and frictionally engaging said slidefway; -pistons in said cylinders; connecting rods between said pistons and said slide plate; one element of a friction clutch secured to one of said discs, the other element of said friction clutch being slidably mounted cof-axially with said axle and being normally restrained from engaging the first oi said elements; yieldable means' continuously tending to eect engage ment oi the elements of the clutch: and means operable from outside the wheel for eiecting the engagement of theclutch elements at will.

6. A wheel comprising a hollow body having sides with'hubs and having an annular connecting said sides to enclose therewith a fluid containing chamber; said wheel having an annular inclined slideway: an' axle on which said ti'ons to stop the rotor; and means to operate said clutch connections to rie-clutch the rotor from the axle. v

3. A wheel having a. rim and sides provided with hubs; an axle on which said wheel is mounted, said wheel and axle enclosing a chamber lor retaining hydraulic iluid; a rotor located within said wheel and rotatably mounted on said axle; an inclined slideway on the inside .0f the wheel: a universally mounted wabbler having a plate frictionally cooperatively engaging said slideway. Said rotor including cylinders and pistons with connecting rods between the pistons and said wabbler, said cylinders having piston controllediluid inlets and having uid outlets; means for ilrst Irlctionally clutching said rotor to said axle and subsequently positively securing said rotor to said axle; means for controlling the escapeiof duid from said cylinders for purposes described; and a valve device common to all said cylinder outlets tor retarding the ow of liquid through said outlets while the clutches are in action.

wheel is rotatably mounted; means to seal the wheel and axle against escape of the liquid contents of the wheel; a rotor including spaced discs having hubs rotatably mounted onsaid axle, cylinders connecting said spaced discs; said cylinders each having fluid inlets and outlets; a wabbler including a yoke pivotally mounted on one of said discs; a slide plate pivotally mounted on said yoke and frictionally engaging said slideway; pistons in said cylinders; connecting rods 4. A chambered wheel having hubs; an axle on on said axle, said rotor including side discs, cylinders connecting the side discs, pistons in said cylinders, a wabbler. and. connecting rods between said pistons and said wabbler, said wabbler bebetween said pistons and said slide plate; one element of a friction clutch secured to one of said discs, the other element of said friction clutch being slidably mounted co-axially with said axle and being normally restrained from engaging the first of said elements; yieldable A means continuously tending to eiect engagement of the elements of the clutch: means op-.

erablefrom-outside the wheel foreiiecting the engagement of the clutch elements at will; and means for retarding more or less the escape of liquid from the cylinders after the rotor has been brought to rest.

7. A wheel comprising a hollow body having sides with hubs and having an annular rim con necting said sides to enclose therewith a duid containing chamber; said wheel having an annular. inclined slldeway; an axle on which said wheel is rotatably mounted; means to seal the wheel and axle against escape of the liquid contents of the wheel; a rotor including spaced discs having hubs rotatably mounted on said axle,

4 l g cylinders connecting said spaced discs, said cylinders each having uid inlets and outlets; a wabbler including a yoke pivotally mounted on one of said discs; a slide plate pivotally mounted on said yoke and frictionally engaging said slideway; pistons in said cylinders; connecting rods between said pistons and said slide plate;one element of a friction clutch secured to one of said dises, the other element of said friction clutch being slidably mounted co-axially with said axle and being normally restrained` from engaging the first of said elements; yieldable means continuously tending to eiIect engagement of the elements ofthe clutch; means operable from outside the wheel for effecting the engagement of the clutch elements at will; and means for positively locking the rotor to the axle after its rotation has been stopped by the friction clutch.l

8. A wheel comprising a hollow body having sides with hubs and having an annular rim connecting said sides to enclose therewith a fluid containing chamber; said Wheel having an annular inclined slideway; an axle on which said wheel is rotatably mounted; means to seal the wheel and axle against escape of the liquid contents of the wheel; a rotor including spaced discs having hubs rotatably mounted on said axle, cylinders connecting said spaced discs, said cylinders each having fluid inlets and outlets; a wabbler including a yoke pivotally mounted on one of said discs; a slide plate pivotally mounted on said yoke and frictionally engaging said slideway; pistons in said cylinders; connecting rods between said pistons and `said slide plate; one element of a friction clutch secured to one of said discs, the other element of said friction clutch being slidably mounted co-axially with said axle and being normally restrained from engaging the first of said elements; yieldable means continuously tending to effect engagement of the elements ofthe clutch; means operable from outside the wheel for eiecting the engagement of the clutch elements at will; means for retarding more or less the escape of liquid from the cylinders after the rotor has'been brought to rest; and means for positively locking the rotor to the axle after its rotation has `been stopped by the friction clutch.

9. A Wheel composed of two side discs having rim iianges, an annular rim center connected to said side discs rim flanges, said sid` discs having hubs, and each of said side discs also having` an inclined slideway; an axle on which said wheel is rotatably mounted; a hydraulically operated key slidably carried by said axle; a rotor which includes spaced apart discs, said rotor discs having hubs journalled on said axle; clutch teeth carried by each of said rotor discs; a united sleeve and ring slidably mounted on said axle and cngaged by said key and having clutch teeth to mesh with the clutch teeth that are carried by said rotor; means continuously `tending' to declutch said teeth; and a hydraulic device connecting said rotor to said wheel with braking effect.

10. A wheel composed of two side'discs having rim ang'es, an annular rim center connected to said side discs rim anges, said side discs having ring slidably mounted on said axle and engaged by said key and having clutch teeth to mesh with the clutch teeth that are carried by said rotor: means continuously tending to de-clutch said teeth; a hydraulic deviceconnecting said rotor to said wheel with braking effect; and a friction clutch element secured to said rotor and a friction clutch element cooperatively mounted on said axle so as to be engaged with the rotor friction clutch element before the toothedclutches become engaged.

11. A wheel composed of two side discs having rim flanges, an annular rim center connected to said side discs rim flanges, said side discs having hubs, and each of said side discs also having an inclined slideway; an axle on which said wheel is rotatably mounted; a

ymanually controlled key slidably carried by said axle; a rotor which includes spaced apart discs. said rotor discs having hubs journalled on said axle; clutch teeth carried by each of said rotor discs; a united sleeve and ring slidably mounted on said axle and engaged by said key and having clutch teeth to mesh with the clutch teeth that are carried by said rotor; means continu'- ously 'tending to de-clutch said teeth; a hydraulic device connecting said rotor to said wheel with braking eiIect; a friction clutch element secured to said rotor and a friction clutch element cooperatively mounted on said axle so as to be engaged with the rotor friction clutch element before the toothed clutches become engaged; and means to permit said second mentioned friction clutch element to be slid along the axle while the toothed clutches are being engaged.

12. A wheel composed of two side discs having rim anges, an annular rim center cou-v nected to said side discs rim flanges, said side discs having hubs, and each of said side discs A also having an inclined slideway; an axle on which said wheel is rotatably mounted; a manually operated key slidably carried by said axle; a rotor which includes spaced apart discs, said rotor discs having hubs journalled on said axle; clutch teeth carried by each of said rotor discs; a united sleeve and ring vslidably mounted on said axle and engaged by said key and having clutch teeth to mesh with the clutch teeth that are carried by said rotor; means continuously tending to de-clutch said teeth; vsaid rotor also including cylinders connecting the rotor discs together andl having .their axes parallel with that of the axle; pistons in said cylinders; universally mounted wabblers having slide plates to engage said slideways; connecting rods behubs, and each of said side discs also having an tween said pistons and said slide plates; said cylinders having oil inlet ports and oil outlet ports; and means for controlling the escape of oil from said cylinders at will.

13. A wheel composed' of two side discs having rim flanges, anannular rim center connected to said side discs rim anges, said side discs having hubs, and each of said side discs also having an inclined slideway; an axle on which said wheel is rotatably mounted; a manually operated key slidably carried by said axle: a rotor which includes spaced apart`discs, said rotor discs having hubs journalled on said axle; clutch teeth carried by each of said rotor discs; a united sleeve and ring slidably mounted on said axle and engaged by said key and having clutch teeth to mesh with the clutch teeth that are carried by said rotor; means continuously tending tode-clutch said teeth; said rotor also to engage said slideways; connecting rods be-` tween said pistons and said slide plates; said cylinders having oil inlet ports and oil outlet ports; and means for controlling the escape of oil from said cylinders at will, said last named means including a valve common to all said oil outlets and carried by said ring.

14. An axle having a bore to provide a piston chamber and having a key slot, a piston in said chamber; a key in said slot; means connecting said piston to said key to move as one; a spring continuously tending to move said key and said piston backwardly; means for admitting hydraulic uiinto said chamber to move said piston and key in opposition to said spring; a wheel rotatably mounted on said axle and having a chamber, said wheel having two slideways spaced apart; a rotor within said chamber between said slideways and including side discs spaced apart and connected together by cylinders having oil inlets and outlets, two wabblers yincluding wabbler slide plates universally mounted on said rotor side discs and slidably engaging said slideways, pistons in said cylinders and connecting rods between said last named pistons and said wabbler slide plates, said rotor being rotatably mounted on said axle normally to turn with the wheel; a sleeve -slidably' mounted on said axle and engaged by said key; a ring on said axle connected to said sleeve to move with it; said sleeve having clutch teeth; cooperating clutch teeth carried by the adjacent rotor side disc; clutch teeth carried by said ring and cooperating clutch teeth carried by the other rotor side disc, said clutch teeth being normally out of mesh; and a valve carried by said sleeve and ring for controlling the oil outlets of the cylinders to retard the escape of oil from the cylinders after the clutch teeth have been meshed.

15. An axle having a bore to provide a piston .chamber` and having a key slot; a piston in said chamber; a key in said slot; means connecting said piston. to said key to move as one; a spring continuously tending to move said key and said piston backwardly; means for admitting hydraulic uid into said chamber to move said piston and key in opposition to said spring; a wheel rotatably mounted on said axle and having a chamber, said wheel having two slideways spaced apart; a'rotor within said chamber between said slideways and including side discs spaced apart and connected together by cylinders having oil inlets and outlets, two wabblers including wabbler slide plates universally mounted on said rotorside discs and slidably engaging said slideways, pistons in said cylinders and connecting rods between said last named pistons and said wabbler slide plates, said rotor being'rotatably mounted on said axle normally to turn with the wheel; a sleeve slidabLv mounted on Vsaid axle and engaged by said key; a ring on said axle connected to said sleeve to move with it; said sleeve having clutch teeth; cooperating clutch teeth carried by the adjacent rotor side disc; clutch teeth carried by said ring and cooperating clutch teeth carried by the other rotor side disc, said clutch teeth being normally o'ut of mesh; a valve carriedby said sleeve and ring for controlling the oil outlets of the cylinders to retard the escape of oil from ,thel cylinders after the clutch teeth have been meshed; a spring-loaded male friction. clutch element slidably keyed to said sleeve; and a female friction clutch element carried by said f rotor, the friction clutch elements being normally out of engagement but arranged to be brought into engagement before said clutch teeth are meshed.'

16. A hollow wheel having an inteal oppositely inclined pair of spaced apart slideways; an axle on which the wheel is journalled; a rotor `including oppositely acting pistons in cylinders and universally mounted wabblers cooperating with said pistons and said slideways, said wabblers and said cylinders and pistonsnormally rotating with the wheel; .operator controlled means for rst stopping the rotation of the rotor on the axle and then locking the rotor to the axle and thereafter diminishing the escape of oil from the cylinders to increase the pressure of the wabblers on the wheel slideways to brake the wheel as desired. f y

17. A hollowgwheel having an. internal oppositely inclined pair of spaced apart slideways; an axle on which the wheel is journalled; a rotor including oppositely acting pistons in cylinders and universally mounted wabblers cooperating with said pistons and said slideways, said y wabblers and said cylinders and pistons normally rotating with the wheel; a friction clutch device between the axle and the rotor; an operator con-- trolled means for actuating said clutch devices for stopping rotation of the rotor and locking it to the axle; and means also controlled by the operator for controlling the escape of oil from the cylinders to eilect a brake application to the wheel.

18. A hollow wheel having an internal oppositely inclined pair of spaced apart slideways; an

axle on which the wheel is `journalled; a rotor including oppositely acting pistons in cylinders and universally mounted wabblers cooperating with said pistons and said slideways, said wabblers and said cylinders and pistons normally rotating with the wheel; a friction clutch device between the axle and the rotor; an operator controlled means for actuating said clutch devices for stopping rotation of the rotor and locking it to the axle; means also controlled lby the operator for controlling the escape of oil from the cylinders to effct a brake application to the wheel; and means independent of the operators controlling means to relieve excessive pressure in the cylinders.

19. A hollow wheel, including inclined discs having at least one inclined slideway; an axle on which the Wheel is rotatably mounted; a; hydraulically operated shifting key slidably carried by said axle; a rotor which includes spaced apart discs, said rotor discs havingv hubs journalled on said axle; clutch teeth carried by said rotor discs; a sleeve slidably keyed to said axle by keys independent of said shifting key, said sleeve being engaged by said shifting key, said sleeve having clutch teeth to mesh with the clutch teeth of said t wheel is rotatably mounted; a manually operated includes spaced apart discs, said rotor discs'having hubs journalled on said axle; clutch teeth earried by each of said rotor discs; a united sleeve and 'ringslidably mounted on said axle and enmesh with the clutch teeth that are carried by said rotr; means continuously tending to declutch said teeth; said rotor also including cylinders connecting theerotdrdiscs together and having their axes parallel with that o! the axle: pistons in said cylinders; universally mounted said slide plates; said cylinders having oil inlet ports and oil outlet ports; means for controlling l the escape of oil. from said cylinders at will, said gaged by said key and having clutchv teeth to last named means including a valve common to 'all said oil outlets and carried by asid ring; and

means to relieve said cylinders ot excessive pressure when the oil outlets of ,the cylinders are l0 closed. Y

cnAyTQN ERASMUS FREDnmcKsoN. 

